Graphite and/or carbon disk with removable wear faces

ABSTRACT

The invention comprises a brake disk assembly in the form of a carbon or graphite disk which is provided on both sides with thin wear plates of carbon or graphite material. The plates are either in segmented or full circle form and are secured to the core by rivets and bushings which also secure the keyway drives of the disks.

United States Patent 1 Cook et a1.

[451 Jan. 23, 1973 1 GRAPHITE AND/OR CARBON DISK WITH REMOVABLE WEARFACES [75] Inventors: Albert W. Cook, Tallmadge; Joseph F. Dernovshek,Akron, both of Ohio [73] Assignee: The Goodyear Tire 8: Rubber Company,Akron, Ohio [22] Filed: Nov. 5, 1970 [21] App1.No.: 87,126

[52] 1.1.5. Cl......l88/25l A, 188/218 XL, 192/107 M [51] Int. Cl ..Fl6d69/02 [58] Field of Search..188/73.2, 218 XL, 264 CC, 251

R, 188/251 A; 192/107 R, 107 M [56] References Cited UNITED STATESPATENTS 2,542,545 2/1951 Lyman ..188/218 XL 3,237,731 3/1966 DuBois188/218 XL 3,478,850 11/1969 Akeel .,...188/264 CC X 3,530,960 9/1970Otto et al. ..188/218 XL 3,548,979 12/1970 Nelson et al. ..188/264 CC3,552,533 1/1971 Nitz ..188/251 A X FOREIGN PATENTS OR APPLICATIONS1,140,969 3/1957 France ..188/218 XL Primary ExaminerGeorge E. A.l-lalvosa Attorney-F. W. Brunner, P. E. Mi11iken and Oldham & Oldham[57] ABSTRACT The invention comprises a brake disk assembly in the formof a carbon or graphite disk which is provided on both sides with thinwear plates of carbon or graphite material. The plates are either insegmented or full circle form and are secured to the core by rivets andbushings which also secure the keyway drives of the disks.

9 Claims, 12 Drawing Figures PATENTEDJMI 23 I975 SHEET 1 OF 2 FIG. 2'

INVENTORS COOK DERNOVSHEK ALBERT W. JOSEPH F.

ATTORNEYS GRAPHITE AND/OR CARBON DISK WITH REMOVABLE WEAR FACES Thisinvention relates to brake assemblies of the type having alternaterotating and stationary brake disks carried between and axially movablebetween a backing plate and a pressure plate. More particularly, theinvention relates to an improved brake disk for use in such an assembly.

With carbon or graphite brake disks of the prior art the entire assemblymust be discarded when the surfaces of the disk have become sufficientlyworn. This, however, involves the discarding of a disk which is stillstructurally sound, and the replacement with a new assembly is extremelyexpensive.

It is the primary object of the invention to provide a graphite orcarbon brake disk in which the wear surfaces of the disk may be renewedor refurbished without requiring the discarding of the entire assembly,thus realizing a considerable cost saving in replacement over the priorart disk assemblies.

In the present invention this object is achieved by providing on acarbon or graphite disk core renewable wear surface disks which may beof the same material as the core which are mechanically secured to thecore and which may be provided for a worn disk, replaced themselves, asnecessary, and all without requiring the discarding of the entire basedisk assembly. The wear surfaces are secured by the bushings and rivetswhich hold the keyway drives to the disks.

A further object of the invention is to provide a method to effectrefurbishment so that disks can have great longevity, and replacementcan be made at minimum cost.

For a more complete understanding of the invention and of the objectsand advantages thereof, reference should be had to the followingspecification and the accompanying drawings wherein there is shown apreferred embodiment of the invention.

In the drawing:

FIG. I is a fragmentary side elevational view of a brake diskconstructed in accordance with the present invention, the disc shownbeing a rotating disk;

FIGS. 2 and 3 are fragmentary sectional views taken along the lines 2--2and 3-3, respectively, of FIG. I and showing the arrangement by whichthe wear plates are attached to the disk core; and

FIGS. 4A, B, C, 5A, B, C and 6A, B, C, represent the method ofrefurbishment of a new solid disk for the first, second, and thirdrefurbishment, respectively.

The reference numeral 10 designates generally a brake disk which is inthe form of an annular ring and which is provided at uniformly spacedintervals on its I outer circumference with slots 12. Keyway drives 14are secured to the annulardisk at each of the slots 12 and held in placeby rivets 16. Each of the keyway;

carbon base material as the core plate 20 and may be v either in theform of annular rings of the same size as the core 20 or in the form ofsegmented rings each forming a part of the annular ring. The wear plates22 may, however, be of a graphite or carbon base designed to providegreater frictional and heat sink capabilities, but not as great astructural capability as the core plate 20. Preferably, the core plate20 will have good resistance to oxidation and great structural strength.The core plate 20 should be a minimum of 1% times the thickness of eachrespective wear plate 22. The wear plates 22 may be full circle orsegmented as long as the segments are secured at both ends by rivets orother appropriate means. In either event, the wear plates 22 aremechanically secured to the core 20 by means of the rivets 16 whichsecure the keyway drives 14 in place. The rivets 16 are not positionedwithin the rubbed face of the plates 22 and hence the plates 22 may bequite thin. Bushings 24 are provided on the, rivets 16 to uniformlydistribute the forcesv between the wear plates 22 and the core plate 20.The wear plates 22 may, for example, be of from 0.075 to 0.175 inchesthick. The overall thickness of the disk assembly may typically bebetween 0.400 and 0.600 inches.

When the wear plates 22 become sufficiently worn that they must bereplaced, it is merely necessary to remove the rivets 16, the bushings24 and the keyway drives 14. The worn wear plates 22 are now discardedand new wear plates placed on either side of the core 20. The keywaydrives 14 are again riveted in place with the bushings 24 and the rivets16 thus securing the new wear plates 22 to the core 20. The brake disk10 is thus renewed and capable of being reused. Since the wear plates 22are relatively thin only a small amount of carbon or graphite materialis actually discarded, the core 20- which forms the bulk disk beingreused.

It should be understood that while the disk illustrated and describedabove is a rotating disk having the keyway drives 14 and keyway slots 18on its. outer circumference, the principles of the invention maybe asadvantageously employed in a stationary brake disk, or one in which thekeyway drives and keyway slots are provided along the innercircumference of the disk.

The method of the invention includes a way to refurbish carbon disksincluding the pressure and end plates. The low coefficient of thermalexpansion and other desirable properties such as the high heat transfercoefficient make a carbon base material ideal from this standpoint. Byrefurbish, it is meant to take an initial solid carbondisk, andrefurbish it according to the techniques defined hereinafter. Thetechnical feasibility of refurbishing has been proved by laboratorydynamic brake testing. Specifically, after the disks went through aspecified brake life, they were refurbished and run through a requireddynamic brake test the second time to determine if the samecharacteristics werepresent.

FIGS. 4A, B, C, 5A, B, C, and 6A, B, C represent the refurbishment cyclewhich is believedto represent the optimum procedure. The firstrefurbishment is illustrated which shows in view 4A a brake diskindicated by numeral 50 which has been worn about 0.060 so that for arotating disk it would have a thickness of about 0.480 inches and for astationary disk about 0.520 inches. The refurbishment technique in itsfirst step will constitute grinding both faces of the disk 50 enough tosmooth it and provide parallel opposite surfaces, or about 0.030 so thatfor a rotating disk the thickness would be approximately 0.450 inchesand for a stationary disk the thickness would be about 0.490 inches. Theinitial thickness is then achieved by refurbishing with a carbon plateor disk 52 as indicated in view 4C that is approximately 0.150 inches inthickness to thereby increase the overall disk thickness by that amount,hence bringing the total disk thickness up to the desired pre-worncondition. The plate 52 is attached in the manner as illustrated inFIGS. 1 through 3, but is attached only on one side as indicated in view4C.

When the disk 50 and plate 52 have again worn as indicated in view 5A toapproximately the same thickness dimensions as in view 4A both the disk50 and plate 52 are ground to the dimensions indicated in view 55, witha new plate 54 being added as in view SC to complete the refurbishing ofthe disk and the return to its initial thickness dimensions. Note,however, that plate 52 is only approximately one-half the thickness ofplate 54. This completes the second refurbishing with a structure whichnow has two wear plates 52 and 54 of different thickness configurations.

The third refurbishment and all subsequent refurbishments areillustrated in FIGS. 6A, B, C where view 6A illustrates the worn disk 50and plates 52 and 54. View 6B illustrates the grinding of plate 54 whileview 6C illustrates the positioning of a new plate 56 in combinationwith plate 54 to achieve the complete refurbishing. In this instance,plate 52 has been discarded because it has worn to such a thin thicknessthat it is no longer structurally usable. Note, however, that the basedisk 50 remains at the same thickness during the third refurbishmentand, of course, for all refurbishments thereafter.

While in accordance with the Patent Statutes, only the best knownembodiment of the invention has been described and illustrated in detailit will be understood that the invention is not so limited. Referenceshould therefore be had to the appended claims in determining the truescope of the invention.

What is claimed is:

l. A brake disk assembly, comprising:

an annular core plate of a carbon based material having substantiallyflat opposite sides;

at least one thin wear plate of a carbon based friction 2. The brakedisk assembly accordingto claim 1 wherein plates are secured to bothsides of the core and each thin plate is in the form of an annular ringof the same configuration as the annular core, and each thin plate is ofsubstantially the same material as the core.

3. The brake disk assembly according to claim 1 wherein plates aresecured to both sides of the core and the thin plates are in the form ofsegments of an annular ring, the thin plates on each side of the coreforming an annular ring of the same configuration as the annular :f Thebrake disk assembly according to claim 1 wherein each thin plate is from0.075 to 0.250 inches thick.

5. A brake disk assembly according to claim 1 where the core has theproperties of being resistant to oxidation and having great structuralstrength, and the thin plate of friction material has the properties ofbeing an excellent heat sink and having good frictional characteristics.

6. A brake disc according to claim 1 where the core is segmented and thethin plate of friction material is segmented, and the means tomechanically secure the thin plate to the core maintain the segments inan annular disc configuration.

7. A brake disk according to claim 1 where the core plate is at leastone and 6 times the thickness of the thin plate of friction material. Ir

8. The brake disk according to claim 1 wherein each keyway drive has apair of side portions extending along opposite sides of the brake diskadjacent l circumference thereof, the rivets extending through thenon-rubbed side portions.

9. The brake disk according to claim 1 wherein bushings extend throughthe thin plates and the annular core to receive the rivets.

a a a a a

2. The brake disk assembly according to claim 1 wherein plates aresecured to both sides of the core and each thin plate is in the form ofan annular ring of the same configuration as the annular core, and eachthin plate is of substantially the same material as the core.
 3. Thebrake disk assembly according to claim 1 wherein plates are secured toboth sides of the core and the thin plates are in the form of segmentsof an annular ring, the thin plates on each side of the core forming anannular ring of the same configuration as the annular core.
 4. The brakedisk assembly according to claim 1 wherein each thin plate is from 0.075to 0.250 inches thick.
 5. A brake disk assembly according to claim 1where the core has the properties of being resistant to oxidation andhaving great structural strength, and the thin plate of frictionmaterial has the properties of being an excellent heat sink and havinggood frictional characteristics.
 6. A brake disc according to claim 1where the core is segmented and the thin plate of friction material issegmented, and the means to mechanically secure the thin plate to thecore maintain the segments in an annular disc configuration.
 7. A brakedisk according to claim 1 where the core plate is at least one and 1/2times the thickness of the thin plate of friction material.
 8. The brakedisk according to claim 1 wherein each keyway drive has a pair of sidePortions extending along opposite sides of the brake disk adjacent 1circumference thereof, the rivets extending through the non-rubbed sideportions.
 9. The brake disk according to claim 1 wherein bushings extendthrough the thin plates and the annular core to receive the rivets.